The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Defects in castings can form as a result of the casting process. Internal defects may not be found from merely inspecting the surface of the casting. Therefore, radiography is often used to inspect castings in order to identify and locate internal defects that a casting may have.
Radiography includes exposing the casting to x-rays in order to produce a radiograph. The radiograph can be reviewed to see if the casting has any defects. However, accurately locating the defects in the casting that are found on the radiograph can be difficult. For example, the radiograph may be a different size than the casting. Furthermore, the orientation of the casting when the radiograph was taken may be difficult to determine.
In order to more accurately locate internal defects of a casting, lead indicators can be taped to the casting. However, numerous radiographs may need to be taken when using lead indicators. A first radiograph is typically taken without any lead indicators taped to the casting. Lead indicators may then be taped to the casting around where the defects are believed to be located, and a second radiograph can be taken. Therefore, more than one radiograph is typically needed to accurately identify locations of defects.
An additional radiograph can also be taken with lead indicators in the area of the defect to perform a parallax shot with the intent of determining the defects relative depth. Parallax principles and methods are further described in Barry, R. and Ruescher, E., “Stereo Radiography,” Nondestructive Testing Handbook, third edition, Vol. 4, Radiographic Testing, Columbus, Ohio, American Society for Nondestructive Testing (2002), p 419-423.
After defect locations are identified, the defect locations of the casting can be reworked or remedied. Although the methods described above can identify locations of defects, at least two radiographs typically need to be taken of the casting in order to obtain an accurate location of the defects which can add cost and complexity to the inspection process of the casting.